Rensselaer Republican, Volume 23, Number 41, Rensselaer, Jasper County, 11 June 1891 — No Need to Be Nervous, Though. [ARTICLE]

No Need to Be Nervous, Though.

Philadelphia Record. It is a curious fact, but one which need make no passenger at all nervous, that the tracks of the Pennsylvania railroad between this city and Pittsburg are more than one-fifth of a mile, or .1,134 feet, to be exact, shorter on an extremely cold dav in winter than on a hot day such as yesterday. It has been found that a steel rail contracts or expands one part in each 148,000 parts with every change of a degree in temperature, and on the 353 miles from here to Pittsburg this amounts to twelve feet six inches for every degree. The difference in the length of the rails on a 90-degree day in winter is, therefore, over 1,100 feet. -The extreme of temperature in Pennsylvania are really much greater than these, and doubtless, therefore, the difference in the length of the rails is even more striking. This contraction and expansion is taken up at the joints.